This invention relates to a clutch system of the friction type placed in a power transmission system.
In the past, a clutch system wherein the frictional force is provided by the force of a spring between the driving friction disk connected to the clutch input member and the driven friction disk connected to the clutch output member, has widely been used. However, in this type of clutch, the set load of the spring must be increased in order to increase the clutch capacity because of restrictions on the diameter of the driving and driven friction disks and the number of disks used. Consequently, clutch decoupling performed against the set load of the spring necessarily requires a greater operating force to the driver's disadvantage.